Prior art systems may be designed according to the following architecture, which shall be described in detail with reference to FIGS. 1a and 1b. 
FIG. 1a describes architecture of one electronic module 1 as discussed in the patent document EP-1145045. This electronic module 1 comprises:                a cover 2 and one electronic board 3 used to digitize and process the data captured by each sensor;        two type of cable sections 4 described in more details in relation with the FIG. 1b;         load distribution means relying on the existence of a rigid part consisting of a metal plate 7, fixed to the connectors 6 thanks to hooking means and studs 8, 9;        tight sealing for the interfaces;        a means of connection 10 for the connection of at least one sensor (not shown).        
It is well understood that other configurations can be made with more than one electronic module (FIG. 1a), for example three electronic modules 1000, 10000 as described in FIG. 1b, thus forming a “link” 100.
This link 100 comprises two types of electronic module 1000, 10000, each one comprising:                a cover 2 and one electronic board 3 used to digitize and process the data captured by each sensor;        two cable sections;        load distribution means relying on the existence of a rigid part consisting of a metal plate 7, fixed to the connectors 6 thanks to hooking means and studs 8, 9;        tight sealing for the interfaces;        a means of connection 10 for the connection of at least one sensor (not shown).        
More precisely, the first type of electronic module 1000 comprises two types of cable section:                a first cable section 4 with:                    at its first extremity, one connector 6 providing the electrical link between the cable 4 and the electronic board 3 positioned inside the cover 2 of the module 1000; and            at its second extremity, one end-of-section hermaphrodite connector 5 adapted to be connected to one other end-of section hermaphrodite connector 5 of one other cable section 4;                        a second cable section 40 with:                    at its first extremity, one connector 6 providing the electrical link between the cable 4 and the electronic board 3 positioned inside the cover 2 of the module 1000; and            at its second extremity, one other connector 6 providing the electrical link between the cable 40 and the electronic board 3 of one other module 10000.                        
More precisely, the second type of electronic module 10000 comprises two identical cable section 40 as described above, each one comprising at its first extremity, one connector 6 providing the electrical link between the cable 40 and the electronic board 3 positioned inside the cover 2 of the module 10000, and at its second extremity, one other connector 6 providing the electrical link between the cable 40 and the electronic board 3 of one other module 1000.
It has to be noted that electronics module should be the same within the same link.
This type of geophysical data acquisition systems using a multitude of these types of electronic modules as defined above performs very well and provides an effective response to market request which requires ease of portability and mechanical robustness during transport and handling, under tensile or bending forces exerted on the cable sections as well as under compressive forces exerted on the cover 2.
Easy portability is characterized by a system having the lowest possible linear mass density and space requirement and high flexibility, and requires only a small workforce for installation.
Mechanical robustness under stress is characterized by the functionality of the cover 2, the connector 6 and the electronic board 3 under a given stress or after it has undergone stress, to remain operational. In certain cases, robustness is also characterized by the preservation of the functions of the electronic board 3 after breakage of the cover 2 under stress, for example under crushing force.
The mechanical behavior of the electronic module 1 as described hitherto differs according to the load applied as shown in FIGS. 2 a-f. More precisely, the value of the moment of inertia of the electronic board 3 is well adapted to characterize the mechanical behavior of the electronic module 1. Indeed, it has to be considered that the moment of inertia characterizes the ability of the geometry of the part, and particularly its cross-section, to withstand mechanical constraints such as bending. In case of a rectangular section, the moment of inertia is proportional to the width and the cube of the thickness as follows:I=(W*T3)/12,
where I corresponds to the moment of Inertia, W the width and T the thickness.
FIG. 2a is a schematic lateral view of the electronic module 1 which undergoes one vertical fall (or vertical impact) (see the arrow F1 on FIG. 2a which shows the direction of this fall/impact). When there is a vertical impact, this one acts on bottom external faces 11 of the connector 6. These surfaces are plane surfaces. The energy transmitted is therefore absorbed by the whole corresponding surface. The deformation of this surface is therefore fairly small. Nevertheless, the moment of inertia subjected to the acceleration of the impact is the minimum moment of the board (as calculated below). The deformation of the electronic board 3 is therefore high, and one bending force is imposed on the electronic components of the electronic board 3.
To illustrate this case, let us consider now an electronic board 3 having a width W of the section characterized by the length 31, typically 75 mm (for example), and a thickness T characterized by the edge length 32, typically 1.6 mm (for example). The value of the resulting moment of inertia is 25.6 mm4 on the above configuration
FIG. 2b is a schematic top view of the electronic module 1 and the stress undergone by the cover 2 in a lateral fall (see the arrow F2 for the direction illustrating a fall). During a lateral fall, the electronic module 1 falls on a rigid external face 12 of the cover 2. Because the external face 12 is made of rigid material, the energy of the fall is absorbed to only a small extent and the acceleration to which the electronic board 3 is subjected is therefore the maximum. As the direction of the impact changes, the dimensions to consider defining the moment of inertia change, particularly the thickness.
If we take the same configuration as described above, the value of the width W still equals to 75 mm, same as describes for a vertical impact, but the value of the thickness T changes to 45 mm (that is to say corresponding to the electronic board 3 width). The value of the resulting moment of inertia is then 569 531.2 mm4.
As can be seen, the value of the moment of inertia of the electronic board 3 for a vertical fall (FIG. 2a) is less important than the value of the moment of inertia for a lateral fall (FIG. 2b). According to the above definition of the moment of inertia, the deformation of the electronic board 3 is therefore less important in the configuration of FIG. 2b. 
In other words, during an impact and in order to reduce the deformation undergone by the electronic board, it is better to place the electronic board perpendicularly to the ground.
FIG. 2c shows a schematic side view of the electronic module 1 and the cover 2 undergoes one tensile or pulling force (illustrated by the arrow F3). Under tensile forces exerted on the cable 4, the main part of the force is transmitted to the cable sections 4 through the load-distributing studs 8, 9 and the plate 7 (illustrated by the arrows F3b). The cover 2 has to cope with very little tension. The electronic board 3, as mounted on the plate 7, should cope with small constraints.
FIGS. 2d and 2e are schematic side views of the electronic module 1 and show the stress undergone by the cover 2 under bending forces towards or opposite to the cover 2 (illustrated by the arrows F4 and F5). A support 13 is situated on the cover 2 of the electronic module 1 (FIG. 2e), or beneath the electronic module 1 in contact with one face of the connector 6 (FIG. 2e). Under a bending force towards or in opposite direction of the cover 2, the resulting forces through the connector 6 are in opposite direction and give rise to a tensile component (see arrows F4a, F5a) at the junction between each cable 4 and each connector 6, or compressive component (see arrows F4b, F5b) at the fastenings of the connector 6 with the plate 7. The plate 7 undergoes bending moments at its extremities.
FIG. 2f is a schematic side view of the electronic module 1 and the stress undergone by cover 2 during compression (illustrated by the arrow F6). During the compression of the cover 2, bending forces are created at the fastenings of the connectors 6. The plate 7 limits these forces by limiting the rotation of the fastenings. The compression is directly transferred to the connectors 6 in the form of a compressive stress (see arrows F6b) and a tensile stress (see arrow F6a) at the junction between each cable 4 and each connector 6.
The number of fastenings (as screws for example) needed to fix the cover to the connectors 6 described here above is important (eight screws in this example of the patent document EP-1145045) in order to withstand numerous forces that go through, as illustrated in FIGS. 2d to 2f. This entails penalties for repairing and troubleshooting.
Thus, the acquisition module described in EP1145045 requires that the design of the different parts should account for a multitude of different forces depending on the load applied to the electronic module 1. The portability is good because of the small space requirement and small weight of the module. However, ease of assembly is penalized by the number of fastenings needed.
Furthermore, the electrical link between the connectors 6 and the electronic board 3 is obtained by means of a connection point on the electronic board that is provided, for a given connector, on the corresponding extremity of the electronic board. The electronic board and the layout of the components on the board therefore take the position of these connection points into consideration. This results in superfluous space being taken on the electronic board.